1. Field of the Invention
The present invention relates to an endoscope system that acquires a first image and a second image in different regions in a same subject and an actuating method for the endoscope system.
2. Description of the Related Art
In recent years, in order to enable observation of a wider range, a wide angle endoscope including a front-view observation optical system and a side-view observation optical system has been proposed.
Examples of the wide angle endoscope include, for example, a type for forming, on one image pickup device, a front-view subject image via a front-view observation window and a side-view subject image via a side-view observation window described in Japanese Patent No. 4782900, and a type in which cameras obtained by combining optical systems and image pickup devices are provided respectively for front view and side view described in Japanese Patent Application Laid-Open Publication No. 2013-542467 (International Publication No. 2012/056453).
Incidentally, when a subject is irradiated by light having constant luminance, in general, illuminance is high in a proximity portion and is low in a remote portion. The proximity portion is more brightly observed and the remote portion is more darkly observed. More specifically, when, for example, a subject having a luminal shape is observed using the wide angle endoscope, an observation region by front view is a remote portion in the axial direction of a lumen and is dark and an observation region by side view is a proximity portion of a lumen inner wall and is bright.
Therefore, for example, International Publication No. 2011/055613 describes an endoscope system that individually detects brightness of a front-view field of view image and brightness of a side-view field of view image and controls, on the basis of a detection result, a light source device such that one field of view image reaches a brightness target value suitable for observation.
Japanese Patent Application Laid-Open Publication No. 2013-066648 describes an image processing apparatus for endoscopes that acquires a forward image corresponding to a forward field of view and a sideward image corresponding to a sideward field of view, performs forward magnification chromatic aberration correction processing when a processing target image signal is the forward image, and performs sideward magnification chromatic aberration correction processing when the processing target image signal is the sideward image.
Further, Japanese Patent Application Laid-Open Publication No. 2001-290103 describes a technique for, in an observation system that observes a front-view forward field of view image with light transmitted through a half mirror and observes an endoscopic image of a liquid crystal monitor with light reflected by the half mirror, changing brightness of an image displayed on the liquid crystal monitor to switch the observation of the forward field of view image and the observation of the endoscopic image.